Biogenic amines (BAs) are nitrogen compounds that are mainly produced by decarboxylation of amino acids or amination and transamination of aldehydes and ketones. These biogenic amines have low molecular weight and are synthesized during the metabolic processes in microorganisms, plants, and animals thus being known as constituting elements which are frequently discovered in their cells.
Among them, putrescine is discovered in gram negative bacteria or fungi and is present in high concentration in various species, and thus putrescine is expected to play an important role in the metabolism of microorganisms. In general, putrescine is an important raw material for the synthesis of polyamine nylon-4,6 and is produced mainly by chemical synthesis. The chemical synthesis is a 3-step process including a catalytic oxidation reaction, a reaction using a cyanide compound, and a hydrogenation reaction using high-pressure hydrogen. Accordingly, there is a demand for the development of a more environment-friendly and energy-effective method involving biomass utilization.
Under these circumstances, various methods for producing putrescine at high concentration by transforming E. coli and a microorganism of the genus Corynebacterium were disclosed (International Patent Publication No. WO 06/005603; International Patent Publication No. WO 09/125924; Qian Z D et al., Biotechnol. Bioeng. 104 (4): 651-662, 2009; Schneider et al., Appl. Microbiol. Biotechnol. 88 (4): 859-868, 2010; Schneider et al., Appl. Microbiol. Biotechnol. 95: 169-178, 2012).
On the other hand, ornithine is a material widely discovered in plants, animals, and microorganisms, and serves as a precursor for biosynthesis of arginine, proline, and polyamine. Additionally, ornithine plays an important role in the pathway of producing urea from amino acids or ammonia and disposing through the ornithine cycle during the in-vivo metabolism of higher organisms. Ornithine is effective in muscle production and reduction of body fat, and thus it has been used as a nutrient supplement and also as a pharmaceutical drug for improving liver cirrhosis and hepatic dysfunction. Methods of producing ornithine include a method of using milk casein as a digestive enzyme and a method of using E. coli or a microorganism of the genus Corynebacterium (Korean Patent No. 10-1372635; T. Gotoh et al., Bioprocess Biosyst. Eng., 33: 773-777, 2010).
E. coli and a microorganism of the genus Corynebacterium are similar in the biosynthetic pathways for producing putrescine or ornithine, but they also exhibit differences as follows. First, the microorganism of the genus Corynebacterium has a “cyclic pathway”, in which glutamic acid is converted into N-acetyl-L-glutamic acid and N-acetyl-L-ornithine is converted into L-ornithine by argJ (bifunctional ornithine acetyltransferase/N-acetylglutamate synthase, EC 2.3.1.35). In contrast, E. coli is involved in the biosynthesis of putrescine or ornithine by a “linear pathway”, in which argA (N-acetylglutamate synthase, EC 2.3.1.1) and argE (Acetylornithine deacetylase, EC 3.5.1.16) replace the role of the argJ in the microorganism of the genus Corynebacterium. 
In the microorganism of the genus Corynebacterium, it is known that an acetyl group recycles between ornithine and glutamic acid in ArgJ. However, in E. coli, ArgA attaches the acetyl group of acetyl-CoA to glutamate in order to produce N-acetylglutamate, and ArgE N-acetyl-ornithine decomposes N-acetyl-ornithine to produce ornithine and acetate (Schneider et al., Appl. Microbiol. Biotechnol. 91, 17-30, 2011).
In particular, pta-ackA (pta, phosphotransacetylase; ackA, acetate kinase) operon and acetyl-coenzyme A synthetase (acs) are known as genes to synthesize acetyl-CoA using acetate.